Method for securing a yoke to a tube using magnetic pulse welding techniques

ABSTRACT

A magnetic pulse welding operation is performed to secure first and second metallic components together, such as a yoke and a driveshaft tube in a vehicular driveshaft assembly. The yoke includes a first portion, such as a body portion, and a second portion, such as a pair of opposed yoke arms. The end of the driveshaft tube is disposed co-axially about the body portion of the yoke. An inductor axially is positioned co-axially about the overlapping portions of the end of the driveshaft tube and the body portion of the yoke. The inductor is energized to perform a magnetic pulse welding operation to secure the end of the driveshaft tube to the body portion of the yoke without generating a significant flow of air toward the inductor.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/362,215, filed Mar. 6, 2002, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

This invention relates in general to the use of magnetic pulse weldingtechniques to secure two metallic components together, such as a yokeand a driveshaft tube in a vehicular driveshaft assembly. In particular,this invention relates to an improved method for performing such amagnetic pulse welding operation that protects the inductor frompotential damage that can result from the performance of this operation.

In most land vehicles in use today, a drive train system is provided fortransmitting rotational power from an output shaft of anengine/transmission assembly to an input shaft of an axle assembly so asto rotatably drive one or more wheels of the vehicle. To accomplishthis, a typical vehicular drive train assembly includes a hollowcylindrical driveshaft tube having first and second end fittings (suchas tube yokes) secured to the opposed ends thereof. The first endfitting forms a portion of a first universal joint, which provides arotatable driving connection from the output shaft of theengine/transmission assembly to the driveshaft tube while accommodatinga limited amount of angular misalignment between the rotational axes ofthese two shafts. Similarly, the second end fitting forms a portion of asecond universal joint, which provides a rotatable driving connectionfrom the driveshaft tube to the input shaft of the axle assembly whileaccommodating a limited amount of angular misalignment between therotational axes of these two shafts.

In vehicular driveshaft assemblies of this general type, it is usuallynecessary to permanently secure the first and second end fittings to theends of the driveshaft tube. Traditionally, conventional weldingtechniques have been used to permanently join the first and second endfittings to the ends of the driveshaft tube. As is well known,conventional welding techniques involve the application of heat tolocalized areas of two metallic members, which results in a coalescenceof the two metallic members. Such conventional welding techniques may ormay not be performed with the application of pressure, and may or maynot include the use of a filler metal. Although conventional weldingtechniques have functioned satisfactorily in the past, there are somedrawbacks to the use thereof in joining the first and second endfittings to the ends of the driveshaft tube. First, as noted above,conventional welding techniques involve the application of heat tolocalized areas of the two metallic members. This application of heatcan cause undesirable distortions and weaknesses to be introduced intothe metallic components. Second, while conventional welding techniquesare well suited for joining components that are formed from similarmetallic materials, it has been found to be somewhat more difficult toadapt them for use in joining components formed from dissimilar metallicmaterials. Third, conventional welding techniques are not easily adaptedfor joining components that have different gauge thicknesses. Inasmuchas the production of vehicular driveshaft assemblies is usually a highvolume process, it would be desirable to provide an improved method forpermanently joining these metallic components together in a manner thatavoids the drawbacks of conventional welding techniques.

Magnetic pulse welding is an alternative process that has been proposedto secure the first and second end fittings to the opposed ends of thedriveshaft tube. To accomplish this, a hollow driveshaft tube having anend portion and an end fitting having a neck portion are initiallyprovided. The end portion of the driveshaft tube can be hollow to allowthe neck portion of the end fitting to be disposed co-axially therein.Alternatively, the neck portion of the end fitting can be hollow toallow the end portion of the driveshaft tube to be disposedtelescopically therein. If desired, one of the adjacent surfaces of theneck portion of the end fitting or the end portion of the driveshafttube can be tapered at least slightly relative to the other. Regardless,an annular gap is provided between the end portion of the driveshafttube and the neck portion of the end fitting. Then, an electricalinductor is provided concentrically about or within the co-axiallyoverlapping portions of the driveshaft tube and the end fitting. Theinductor is energized to generate a magnetic field that either collapsesthe outer member inwardly into engagement with the inner member orexpands the inner member outwardly into engagement with the outermember. In either event, the high velocity impact of the two members, aswell as the large pressure exerted thereon, cause them to becomepermanently joined together. When one of the adjacent surfaces istapered, the energization of the inductor causes the two members tocollide one another in an axially progressive manner from one end of thetapered surface to the other. This slanting type of collision is one ofthe physical conditions that is usually necessary to achieve a strong,high-quality weld in the process of magnetic pulse welding.

As mentioned above, prior to being joined together, the two componentsare initially spaced apart from one another such that an annular gapexists between the adjacent surfaces thereof. This gap typically filledwith air. Also, the adjacent surfaces of the two components are usuallycovered with oxide films or other contaminants. To achieve a strong weldbetween the two components using magnetic pulse welding (or, for thatmatter, any other type of cold welding process), it is important toremove these films and contaminants from the adjacent surfaces of thetwo components.

When the inductor is energized to form the pulsed magnetic field, thehigh velocity movement between the two components rapidly closes theannular gap, causing the air that was initially present in the gap to bequickly expelled outwardly therefrom. In the area where the surfacescollide with high velocity at a tapered angle, a circular cumulativeflow of air is created. Fortunately, during this expulsion of the airfrom the annular gap, a very effective cleaning process occursautomatically as a result of the slanting collision of the adjacentsurfaces of the two components to be welded. Specifically, the circularcumulative flow of air functions to remove the oxide films and othercontaminants from the adjacent surfaces of the two components functionsto clean such surfaces directly before the welding process occurs, whichis the best type of cleaning.

This cumulative flow of air and contaminants possesses a large amount ofenergy and supersonic velocity. For example, it creates a loud soundlike thunder if the flow is allowed to escape to the atmosphere. If thecumulative flow is reflected from an obstacle, such as a shoulder formedon the end fitting or one or more surfaces of tooling for performing themagnetic pulse welding operation, it can be directed toward the inductorthat generated the magnetic field. In this instance, the insulation andother elements of the inductor can be contaminated and otherwiseadversely affected in a short number of welding cycles. For example,insulation provided on the inductor can degrade significantly fast ifthe air and other portions of the cumulative flow are captured inside aclosed space, the volume of which decreases fast. This situation istypical when, for example, the yoke shoulder is used as a stop tofacilitate pre-assembly of the parts to be welded inside the inductor.In this case, a very powerful secondary flow is created as a result of agas breakdown at the end of the collision of the welded parts through avery narrow circular gap between the shoulder and the end of the tube.Similar to the cumulative flow, this secondary flow is circular, hashigh velocity, and has high temperature. Unlike the cumulative flow,which is directed axially, the secondary flow is directed radially,i.e., perpendicular to the inductor insulation. The secondary flow ishighly concentrated in an axial direction and acts as a sharp circularrazor. The secondary flow can literally cut the inductor insulationwithin several welding cycles. Obviously, this is unacceptable in amanufacturing process because breakdown of the inductor is possible.

In order to prevent this from occurring, it has been suggested toprovide a nonmetallic, annular shield between the axially overlappingportions of the two components and the inductor during the magneticpulse welding process. The high velocity secondary flow created duringthe magnetic pulse welding operation impinges upon the shield, thusprotecting the inductor therefrom premature. However, the use of such ashield has been found to be relatively time-consuming and, therefore,relatively inefficient, particularly in the context of the high volumeproduction process associated with the manufacture of vehiculardriveshaft assemblies. Thus, it would be desirable to provide animproved method for performing a magnetic pulse welding operation thatreduces or eliminates the possibility of the cumulative flow escaping,as well as the possibility of forming a secondary flow in the directionof the inductor, thereby protecting the inductor from the potential wearand damage that breakdown can result therefrom.

SUMMARY OF THE INVENTION

This invention relates to an improved method for performing a magneticpulse welding operation to secure two metallic components together, suchas a yoke and a driveshaft tube in a vehicular driveshaft assembly, thatprotects the inductor from potential damage that can result from theperformance of this operation. The yoke includes a first portion, suchas a body portion, and a second portion, such as a pair of opposed yokearms. The end of the driveshaft tube is disposed co-axially about thebody portion of the yoke. An inductor axially is positioned co-axiallyabout the overlapping portions of the end of the driveshaft tube and thebody portion of the yoke. The inductor is energized to perform amagnetic pulse welding operation to secure the end of the driveshafttube to the body portion of the yoke without generating a significantflow of air toward the inductor. To accomplish this, the yoke can beformed having an annular shoulder, and the end of the driveshaft tubecan be urged into abutment with the shoulder to define an annular spacetherebetween. If desired, the yoke can also include an annular step, andthe end of the driveshaft tube can extend about the annular step so asto define the annular space. Alternatively, the yoke can be formedhaving an annular shoulder, and the end of the driveshaft tube canextend about the annular shoulder to define an annular spacetherebetween.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiments, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a first embodiment of an endfitting and a driveshaft tube shown prior to being assembled and securedtogether by means of a magnetic pulse welding operation in accordancewith the method of this invention.

FIG. 2 is an enlarged sectional elevational view of the first embodimentof the end fitting and the driveshaft tube illustrated in FIG. 1 shownassembled and disposed within an inductor for performing the magneticpulse welding operation.

FIG. 3 is a further enlarged sectional elevational view showing portionsof the first embodiment of the end fitting, the driveshaft tube, and theinductor illustrated in FIGS. 1 and 2 prior to the commencement of themagnetic pulse welding operation.

FIG. 4 is an enlarged sectional elevational view similar to FIG. 3showing portions of the first embodiment of the end fitting, thedriveshaft tube, and the inductor after the performance of aconventional magnetic pulse welding operation that results in thegeneration of a highly intensive gas spray that can damage the inductor.

FIG. 5 is an enlarged sectional elevational view similar to FIG. 4showing portions of the first embodiment of the end fitting, thedriveshaft tube, and the inductor after the performance of a magneticpulse welding operation that reduces or eliminates the generation of theintensive spray of air in accordance with the method of this invention.

FIG. 6 is an enlarged sectional elevational view similar to FIG. 3showing portions of a second embodiment of the end fitting, thedriveshaft tube, and the inductor prior to the commencement of themagnetic pulse welding operation in accordance with the method of thisinvention.

FIG. 7 is an enlarged sectional elevational view similar to FIG. 4showing portions of the second embodiment of the end fitting, thedriveshaft tube, and the inductor illustrated in FIG. 6 after theperformance of a magnetic pulse welding operation in accordance with themethod of this invention.

FIG. 8 is an enlarged sectional elevational view similar to FIG. 3showing portions of a third embodiment of the end fitting, thedriveshaft tube, and the inductor prior to the commencement of themagnetic pulse welding operation in accordance with the method of thisinvention.

FIG. 9 is an enlarged sectional elevational view showing portions of thethird embodiment of the end fitting, the driveshaft tube, and theinductor illustrated in FIG. 8 after the performance of the magneticpulse welding operation in accordance with the method of this invention.

FIG. 10 is an enlarged sectional elevational view similar to FIG. 3showing portions of a fourth embodiment of the end fitting, thedriveshaft tube, and the inductor prior to the commencement of themagnetic pulse welding operation in accordance with this invention.

FIG. 11 is an enlarged sectional elevational view showing portions ofthe fourth embodiment of the end fitting, the driveshaft tube, and theinductor illustrated in FIG. 10 after the performance of the magneticpulse welding operation in accordance with the method of this invention.

FIG. 12 is an enlarged sectional elevational view similar to FIG. 3showing portions of a fifth embodiment of the end fitting, thedriveshaft tube, and the inductor prior to the commencement of themagnetic pulse welding operation in accordance with this invention.

FIG. 13 is an enlarged sectional elevational view showing portions ofthe fifth embodiment of the end fitting, the driveshaft tube, and theinductor illustrated in FIG. 12 after the performance of the magneticpulse welding operation in accordance with the method of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, there is illustrated in FIGS. 1 and 2 aportion of a vehicular driveshaft assembly 10 that includes a driveshafttube, indicated generally at 20, and a first embodiment of an endfitting, indicated generally at 30. Although this invention will bedescribed and illustrated in the context of securing an end fitting to adriveshaft tube to form a portion of a vehicular driveshaft assembly, itwill be appreciated that the method of this invention can be used tosecure any two metallic components together for any desired purpose orapplication.

The illustrated driveshaft tube 20 is generally hollow and cylindricalin shape and can be formed from any desired metallic material, such as6061 T6 aluminum alloy, for example. Preferably, the driveshaft tube 20has an outer surface that defines a substantially constant outerdiameter and an inner surface that defines a substantially constantinner diameter. Thus, the illustrated driveshaft tube 20 has asubstantially cylindrical and uniform wall thickness, although such isnot required. The driveshaft tube 20 has an end portion 21 thatterminates at an end surface 22.

The illustrated end fitting 30 is a tube yoke formed from a metallicmaterial that can be either the same as or different from the metallicmaterial used to form the driveshaft tube 20, such steel or an alloy ofaluminum, for example. The end fitting 30 includes a body portion 31having a pair of opposed yoke arms 32 that extend therefrom in a firstaxial direction. A pair of aligned openings 33 are formed through theyoke arms 32 and are adapted to receive conventional bearing cups (notshown) of a universal joint cross therein. If desired, an annular groove33a (see FIG. 2) can be formed within each of the openings 33 tofacilitate retention of the bearing cups therein in a known manner bymeans of respective snap rings (not shown). A generally hollow neckportion 34 extends axially in a second axial direction from the bodyportion 31. The structure of the neck portion 34 is described in detailbelow. If desired, an annular groove 35 (see FIG. 2) or similar recessedarea can be formed on the interior of the end fitting 30. The purposefor this annular groove 35 is explained in detail in co-pendingapplication Ser. No. 60/362,150, filed Mar. 6, 2002, which is also ownedby the assignee of this invention. The disclosure of that application isalso incorporated herein by reference.

FIG. 3 illustrates the structure of the neck portion 34 of the endfitting 30 in more detail, albeit in a somewhat exaggerated manner. Asshown therein, the neck portion 34 of the end fitting 30 preferably hasan outer surface including a first tapered portion 34a that tapersoutwardly from a relatively small outer diameter adjacent to the bodyportion 31 to an outermost point 34b. The outer surface of the neckportion 34 further include a second tapered portion 34c that tapersinwardly from the outermost point 34b to the axial end of the neckportion 34. The outer surface of the neck portion 34 is preferablysmaller in diameter than the outer diameter of the body portion 31. As aresult, an annular shoulder 34d is defined between the neck portion 34and the body portion 31 of the end fitting 30.

The outermost point 34b of the neck portion 34 can, if desired, definean outer diameter that is either approximately equal to or slightlysmaller in diameter than the inner diameter defined by the inner surfaceof the end portion 21 of the driveshaft tube 20. Thus, when the endportion 21 of the driveshaft tube 20 is disposed about the neck portion34 of the end fitting 30 as shown in FIGS. 2 and 3, the two componentsare positively located relative to one another. However, the outerdiameter defined by the outermost point 34b of the neck portion 34 can,if desired, be somewhat smaller in diameter than the inner diameterdefined by the inner surface of the end portion 21 of the driveshafttube 20. In such instance, an external fixture (not shown) may beprovided for positively positioning the end portion 21 of the driveshafttube 20 and the neck portion 34 of the end fitting 30 relative to oneanother. The second tapered portion 34c of the outer surface of the neckportion 34 is provided to facilitate the axial installation of the endportion 21 of the driveshaft tube 20 onto the neck portion 34 of the endfitting 30 in an known manner. The hollow neck portion 34 of the endfitting 30 may have a substantially uniform wall thickness, althoughsuch is not required. This tapered outer surface of the neck portion 34aof the end fitting 30 has been found to provide good results during theperformance of a magnetic welding process that is discussed in detailbelow. A more detailed explanation of the structure of the neck portion34 of the end fitting 30 can be found in U.S. Pat. No. 5,981,921 toYablochnikov. The disclosure of that patent is incorporated herein byreference.

Typically, the end portion 21 of the driveshaft tube 20 is installedonto the neck portion 34 of the end fitting 30 by moving it axiallythereover until the end surface 22 of the driveshaft tube 20 abuts theshoulder 34d on the end fitting 30 as shown in FIGS. 2 and 3, althoughsuch is not required. When the driveshaft tube 20 and the end fitting 30are assembled in this manner, an annular gap or space 36 (see FIG. 3) isdefined between the inner surface of the end portion 21 of thedriveshaft tube 20 and outer surface of the neck portion 34 of the endfitting 30. The size of the gap 36 can vary in radial dimension with thetapered shape of the outer surface of the neck portion 34 of the endfitting 30, although such is not required. Typically, the radialdimension of such gap 36 will be up to a maximum of about fivemillimeters, although the gap 36 may have any desired dimension.Preferably, the gap 36 is substantially uniform circumferentially aboutthe axially overlapping portions of the end portion 21 of the driveshafttube 20 and the neck portion 34 of the end fitting 30, although such isnot required.

FIG. 2 3 also illustrates an inductor 40 disposed about the assembly ofthe driveshaft tube 20 and the first embodiment of the end fitting 30prior to the performance of a magnetic pulse welding operation forsecuring the two components together in accordance with the method ofthis invention. The inductor 40 can be formed having any desiredstructure, such as that shown and described in U.S. Pat. No. 4,129,846to Yablochnikov. The disclosure of that patent is incorporated herein byreference. The inductor 40 is connected to a schematically illustratedcontrol circuit for selectively operating same. As shown in FIG. 2, afirst end of the inductor 40 is connected to a first electricalconductor 41, while a second end of the inductor 40 is connected througha discharge switch 42 to a second electrical conductor 43. A pluralityof high voltage capacitors 44 or similar energy storage devices areconnected between the first and second electrical conductors 41 and 43.The first electrical conductor 41 is also connected to a source ofelectrical energy 45, while the second electrical conductor 43 isconnected through a charging switch 46 to the source of electricalenergy 45. The structure and operation of the control circuit isdescribed in detail in U.S. Pat. No. 5,981,921 to Yablochnikov, and thedisclosure of that patent is also incorporated herein by reference.

The operation of the inductor 40 to perform the magnetic pulse weldingoperation is well known in the art, and reference is again made to theabove-referenced U.S. Pat. No. 5,981,921 to Yablochnikov for a detailedexplanation. Briefly, however, the inductor 40 is operated by initiallyopening the discharge switch 42 and closing the charging switch 46. Thisallows electrical energy to be transferred from the source of electricalenergy 45 to each of the capacitors 44. When the capacitors 44 have beencharged to a predetermined voltage, the charging switch 46 is opened.Thereafter, when it is desired to operate the inductor 40, the dischargeswitch 42 is closed. As a result, a high energy pulse of electricalcurrent flows from the capacitors 44 through the inductor 40, therebygenerating an immense and momentary electromagnetic field about the endportion 21 of the driveshaft tube 20.

This electromagnetic field exerts a very large force on the outersurface of the end portion 21 of the driveshaft tube 20, causing it tocollapse inwardly at a high velocity onto the neck portion 34 of the endfitting 30, as shown in FIG. 4. The resulting impact of the innersurface of the end portion 21 of the driveshaft tube 20 with the outersurface of the neck portion 34 of the end fitting 30 causes a weld ormolecular bond to occur therebetween, such as shown at the region 47 inFIG. 4. The size and location of the weld region 47 will vary with avariety of factors, such as the size of the gap 36, the size, shape, andnature of the metallic materials used to form the driveshaft tube 20 andthe end fitting 30, the size and shape of the inductor 40, the angle andvelocity of the impact between the end portion 21 of the driveshaft tube20 and the neck portion 34 of the end fitting 30, and the like. It willbe appreciated that the illustrated weld region 47 is intended to berepresentative of an exemplary prime welding area that provides the bestpossible adherence of the driveshaft tube 20 to the end fitting 30, andthat other areas of the driveshaft tube 20 and the end fitting 30 mayalso be welded together as well during this process.

Prior to the energization of the inductor 40 to perform a magnetic pulsewelding operation, the annular gap 36 between the inner surface of thedriveshaft tube 20 and the outer surface of the end fitting 30 istypically filled with air. Also, the adjacent inner surface of thedriveshaft tube 20 and the outer surface of the end fitting 30 areusually covered with oxide films or other contaminants. To achieve astrong weld between these two components using magnetic pulse welding(or, for that matter, any other type of cold welding process), it isimportant to remove these films and contaminants from the adjacentsurfaces. When the inductor 40 is energized to form the pulsedelectromagnetic field as described above, the inner surface of thedriveshaft tube 20 and the outer surface of the end fitting 30 engageone another at a relatively high velocity. This high velocity relativemovement rapidly closes the annular gap 36, causing the air and the restof the cumulative flow to be captured inside a closed space, the volumeof which decreases rapidly and, therefore, becomes relatively small,such as shown in FIG. 4. As a result, a high velocity, high temperaturesecondary flow, such as shown at 48 in FIG. 4, can be sprayed generallyradially outwardly from between the driveshaft tube 20 and the endfitting 30 during the magnetic pulse welding operation. Because theinductor 40 is typically disposed in a relatively close proximity aboutthe driveshaft tube 20 and the end fitting 30 during the magnetic pulsewelding operation, this secondary flow 48 may impinge upon the innersurface of the inductor 40. As a result, the inductor 40 can sufferpremature wear and damage.

This invention contemplates several alternative methods for reducing oreliminating the occurrence of this high velocity secondary flow 48 so asto protect the inductor 40 from premature wear and damage during theperformance of the magnetic pulse welding operation. FIG. 5 illustratesthe driveshaft tube 20 and the first embodiment of the end fitting 30after the inductor 40 has been energized in the manner described aboveto perform a magnetic pulse welding operation in accordance with themethod of this invention. As shown therein, the end surface 22 of thedriveshaft tube 20 has been collapsed into engagement with a portion ofthe shoulder 34d of the end fitting 30, while the remainder of the endportion 21 of the driveshaft tube 20 has been collapsed into engagementwith the outer surface of the neck portion 34 of the end fitting 30 asdescribed above. As a result, the air that was present in the gap 36before the commencement of the magnetic pulse welding operation and therest of the cumulative flow are captured, either partially orcompletely, in an annular space 49 defined between the inner surface ofthe end portion 21 of the driveshaft tube 20, the outer surface of theneck portion 34 of the end fitting 30, and the interior portion of theshoulder 34d of the end fitting 30. The air and particles of mattercontained in the annular space 49 are, therefore, not rapidly expelled(or at least not as rapidly expelled) from the gap 36 during themagnetic pulse welding operation in the manner of the high velocitysecondary flow 48 described above. Thus, the air and particles of mattercontained in the annular space 49 will not damage the inductor 40 aspreviously discussed. The end surface 22 of the driveshaft tube 20 canbe caused to collapse into engaged with the shoulder 34d of the endfitting 30 by urging the end fitting 30 axially into engagement withsuch shoulder 34d prior to and during the magnetic pulse weldingoperation or in any other desired manner.

FIG. 6 is an enlarged sectional elevational view similar to FIG. 3showing a second embodiment of the end fitting, indicated generally at30′, that can be used in the method of this invention. The secondembodiment of the end fitting 30′ is generally similar to the firstembodiment of the end fitting 30 described above, and like referencenumbers are used to illustrate similar structures therein. However, theneck portion 34 of the modified end fitting 30′ has a recess 50 formedin the outer surface thereof. In the illustrated embodiment, the recess50 is annular in shape, extending about the entire outer surface of theneck portion 34. However, the recess 50 need not extend about the entireouter surface of the neck portion 34, but rather may extend about only aportion thereof. Furthermore, a plurality of individual recesses 50 maybe provided on the outer surface of the neck portion 34 if desired. Inthe illustrated embodiment, the recess 50 is formed in the outer surfaceof the neck portion 34 adjacent to the shoulder 34d. However, the recess50 may be formed at any desired location in the outer surface of theneck portion 34.

FIG. 7 illustrates the driveshaft tube 20 and the modified end fitting30′ after the inductor 40 has been energized in the manner describedabove to perform a magnetic pulse welding operation in accordance withthe method of this invention so as to reduce or eliminate the generationof the high velocity secondary flow 48 shown in FIG. 4. As showntherein, the end surface 22 of the driveshaft tube 20 has been collapsedinto engagement with a portion of the shoulder 34d of the end fitting30′, while the remainder of the end portion 21 of the driveshaft tube 20has been collapsed into engagement with the outer surface of the neckportion 34 as described above. As a result, the air that was present inthe gap 36 before the commencement of the magnetic pulse weldingoperation and the rest of the cumulative flow are captured, eitherpartially or completely, in an annular space 51 defined between theinner surface of the end portion 21 of the driveshaft tube 20, therecess 50 formed in the outer surface of the neck portion 34 of themodified end fitting 30′, and the shoulder 34d of the end fitting 30. Aspreviously discussed, such contained air and the rest of the cumulativeflow will not be rapidly expelled (or at least not as rapidly expelled)from the annular space 51 and, therefore, will not damage the inductor40 in the manner of the high velocity secondary flow 48 described above.

FIG. 8 is an enlarged sectional elevational view similar to FIG. 3showing a third embodiment of the end fitting, indicated generally at30″, that can be used in the method of this invention. The thirdembodiment of the end fitting 30″ is generally similar to the firstembodiment of the end fitting 30 described above, and like referencenumbers are used to illustrate similar structures therein. However, theneck portion 34 of the modified end fitting 30″ has an annular step 60formed in the outer surface thereof. The illustrated step 60 has agenerally radially outwardly facing surface 60a that is tapered slightlyto facilitate the installation of the end portion 21 of the driveshafttube 20 thereover and to positively position the end portion 21 of thedriveshaft tube 20 on the neck portion 34 of the end fitting 30. Toaccomplish this, the generally radially outwardly facing surface 60a canbe tapered at an angle in the range of from about five degrees to aboutnine degrees relative to the inner circumferential surface of the endportion 21 of the driveshaft tube 20, for example.

The illustrated step 60 also has a generally axially facing surface 60bthat extends generally radially relative to an axis of rotation definedby the driveshaft tube 20 and the modified end fitting 30″. In theillustrated embodiment, the step 60 is annular in shape, extending aboutthe entire outer surface of the neck portion 34. However, the step 60need not extend about the entire outer surface of the neck portion 34,but rather may extend about only a portion thereof. In the illustratedembodiment, the step 60 is formed in the outer surface of the neckportion 34 adjacent to the shoulder 34d. However, the step 60 may beformed at any desired location in the outer surface of the neck portion34.

FIG. 9 illustrates the driveshaft tube 20 and the modified end fitting30″ after the inductor 40 has been energized in the manner describedabove to perform a magnetic pulse welding operation in accordance withthe method of this invention so as to reduce or eliminate the generationof the high velocity secondary flow 48 shown in FIG. 4. As showntherein, the end surface 22 of the driveshaft tube 20 has been collapsedinto engagement with the step 60 of the end fitting 30″, while theremainder of the end portion 21 of the driveshaft tube 20 has beencollapsed into engagement with the outer surface of the neck portion 34as described above. During this operation, the step 60 may be somewhatdeformed, as shown in FIG. 9. As a result, the air that was present inthe gap 36 before the commencement of the magnetic pulse weldingoperation and the rest of the cumulative flow are captured, eitherpartially or completely, in an annular space 61 defined between theinner surface of the end portion 21 of the driveshaft tube 20, the step60, and the outer surface of the neck portion 34 of the modified endfitting 30″. As previously discussed, such contained air and the rest ofthe cumulative flow will not be rapidly expelled from the annular space61 and, therefore, will not damage to the inductor 40 in the manner ofthe high velocity secondary flow 48 described above.

The provision of the step 60 on the third embodiment of the end fitting30″ will typically provide for better containment of the air and therest of the cumulative flow that were present in the gap 36 before thecommencement of the magnetic pulse welding operation than the first andsecond embodiments of the end fitting 30 and 30′ described above.However, because the end portion 21 of the driveshaft tube 20 initiallyabuts the radially outwardly facing surface 60a of the step 60 on thethird embodiment of the end fitting 30″ during the magnetic pulsewelding operation (instead of being free to move radially inwardly aswith the first and second embodiments of the end fitting 30 and 30′described above), it will be appreciated that the provision of this step60 may require the use of additional electrical energy to insure thatthe interior portion of the inner surface of the driveshaft tube 20abuts the outer surface of the modified end fitting 30″ at a sufficientvelocity as to complete the magnetic pulse welding operation.

To minimize the amount of additional electrical energy to perform themagnetic pulse welding operation, a groove (shown in phantom at 62 inFIGS. 8 and 9) can be formed in the step 60 on the third embodiment ofthe end fitting 30″. The groove 62 can extend continuously about thecircumference of the end fitting 30″ or only partially thereabout.Furthermore, the groove 62 can be embodied as a plurality ofdiscontinuous recesses formed about the circumference of the end fitting30″. The purpose of the groove 62 is to mechanically weaken the step 60,thereby allowing the step 60 to be more easily deformed when themagnetic pulse welding operation is performed. Such deformation willminimize the amount of additional electrical energy to perform themagnetic pulse welding operation, while still providing the step 60 forbetter containment of the air and cumulative flow in the annular space61.

FIG. 10 is an enlarged sectional elevational view similar to FIG. 3showing a fourth embodiment of the end fitting, indicated generally at30′″, that can be used in the method of this invention. The fourthembodiment of the end fitting 30′″ is generally similar to the firstembodiment of the end fitting 30 described above, and like referencenumbers are used to illustrate similar structures therein. However, theneck portion 34 of the modified end fitting 30′″ has a modified step 70formed in the outer surface thereof. The modified step 70 has agenerally radially outwardly facing surface 70a that is tapered slightlyto facilitate the installation of the end portion 21 of the driveshafttube 20 thereover, similar to the generally radially outwardly facingsurface 60a described above. The modified step 70 also has a generallyaxially facing surface 70b that is angled somewhat concavely relative toan axis of rotation defined by the driveshaft tube 20 and the endfitting 30′″. For example, the generally axially facing surface 70b canbe tapered at an angle in the range of from about thirty degrees toabout sixty degrees relative to the axis of rotation defined by thedriveshaft tube 20 and the modified end fitting 30′″. In the illustratedembodiment, the modified step 70 is annular in shape, extending aboutthe entire outer surface of the neck portion 34 of the modified endfitting 30′″. However, the modified step 70 need not extend about theentire outer surface of the neck portion 34, but rather may extend aboutonly a portion thereof.

FIG. 11 illustrates the driveshaft tube 20 and the modified end fitting30′″ after the inductor 40 has been energized in the manner describedabove to perform a magnetic pulse welding operation in accordance withthe method of this invention so as to reduce or eliminate the generationof the high velocity secondary flow 48. As shown therein, the endsurface 22 of the driveshaft tube 20 has been collapsed into engagementwith the modified step 70 of the end fitting 30′″, while the remainderof the end portion 21 of the driveshaft tube 20 has been collapsed intoengagement with the outer surface of the neck portion 34 as describedabove. During this operation, the modified step 70 may be somewhatdeformed, as shown in FIG. 11. As a result, the air that was present inthe gap 36 before the commencement of the magnetic pulse weldingoperation and the rest of the cumulative flow are captured, eitherpartially or completely, in an annular space 71 defined between theinner surface of the end portion 21 of the driveshaft tube 20, themodified step 70, and the outer surface of the neck portion 34 of themodified end fitting 30′″. As previously discussed, such contained airand cumulative flow will not be rapidly expelled from the annular space71 and, therefore, will not damage the inductor 40 in the manner of thehigh velocity secondary flow 48 described above.

Because of the concave shape of the modified step 70, the provision of agroove in the modified step 70 (such as the groove 62 in the step 60described above and shown in FIGS. 8 and 9) may not be necessary ordesirable. However, such a groove may be provided in the modified step70 if desired.

FIG. 12 is an enlarged sectional elevational view similar to FIG. 3showing a fifth embodiment of the end fitting, indicated generally at30″″, that can be used in the method of this invention. The fifthembodiment of the end fitting 30″″ is generally similar to the firstembodiment of the end fitting 30 described above, and like referencenumbers are used to illustrate similar structures therein. In thisembodiment, however, the end portion 21 of the driveshaft tube 20 doesnot abut the annular shoulder 34d that is defined between the neckportion 34 and the body portion 31 of the end fitting 30, but ratherextends axially beyond such annular shoulder 34d. To facilitate this,the outer surface of the body portion 31 of the end fitting 30 may havea generally radially outwardly facing surface 80 that is taperedslightly to facilitate the installation of the end portion 21 of thedriveshaft tube 20 thereover. The generally radially outwardly facingsurface 80 can be tapered at an angle in the range of from about fivedegrees to about nine degrees relative to the inner circumferentialsurface of the end portion 21 of the driveshaft tube 20, for example.

FIG. 13 illustrates the driveshaft tube 20 and the modified end fitting30″″ after the inductor 40 as been energized in the manner describedabove to perform a magnetic pulse welding operation in accordance withthe method of this invention so as to reduce or eliminate the generationof the high velocity secondary flow 48 shown in FIG. 4. As showntherein, the end portion 21 of the driveshaft tube 20 has been collapsedinto engagement with the tapered outer surface 34a of the neck portion34 as described above. During this operation, the annular shoulder 34dmay be somewhat deformed, as shown in FIG. 13. As a result, the air thatwas present in the gap 36 before the commencement of the magnetic pulsewelding operation and the rest of the cumulative flow are captured,either partially or completely, in an annular space 81 defined betweenthe inner surface of the end portion 21 of the driveshaft tube 20, theannular shoulder 34d, and the outer surface of the neck portion 34 ofthe modified end fitting 30″″. As previously discussed, such containedair and the rest of the cumulative flow will not be rapidly expelledfrom the annular space 81 and, therefore, will not damage to theinductor 40 in the manner of the high velocity secondary flow 48described above.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiment. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.

1. A method of performing a magnetic pulse welding operation to securefirst and second metallic components together comprising the steps of:(a) providing a first metallic component including a first portionhaving a shoulder and a second portion; (b) providing a second metalliccomponent having an end; (c) disposing the end of the second metalliccomponent in an axially overlapping manner relative to the first portionof the first metallic component; (d) providing an inductor axiallycoaxially relative to the end of the second metallic component and thefirst portion of the first metallic component; and (e) energizing theinductor to perform a magnetic pulse welding operation to secure the endof the second metallic component to the first portion of the firstmetallic component and to cause the end of the second metallic componentto engage the shoulder to prevent a significant flow of air toward theinductor.
 2. The method defined in claim 1 wherein said step (c) isperformed by disposing the end of the second metallic component inabutment with the shoulder provided on the first portion of the firstmetallic component.
 3. The method defined in claim 1 wherein said step(c) is performed by disposing the end of the second metallic componentaxially beyond the shoulder provided on the first portion of the firstmetallic component.
 4. The method defined in claim 3 wherein said step(a) is performed by providing the second portion of the first metalliccomponent with a tapered surface, and wherein said step (c) is performedby disposing the end of the second metallic component in engagement withthe tapered surface.
 5. The method defined in claim 1 wherein said step(a) is performed by providing the first portion of the first metalliccomponent with an outer surface having a recess, and wherein said step(e) is performed by causing the end of the second metallic component toengage the shoulder and a portion of the first metallic component todefine a space that includes the recess.
 6. The method defined in claim1 wherein said step (a) is performed by providing a shoulder having astep, and wherein said step (e) is performed by causing the end of thesecond metallic component to engage the step of the shoulder and aportion of the first metallic component to define a space.
 7. The methoddefined in claim 6 wherein said step (a) is performed by providing thestep having a groove formed therein.
 8. The method defined in claim 6wherein said step (a) is performed by providing the step having aplurality of grooves formed therein.
 9. The method defined in claim 6wherein said step (a) is performed by providing the step having agenerally axially facing surface that is angled relative to an axis ofrotation defined by the first and second metallic components.
 10. Themethod defined in claim 6 wherein said step (a) is performed byproviding the step having a generally axially facing surface that isangled concavely relative to an axis of rotation defined by the firstand second metallic components.
 11. The method defined in claim 6wherein said step (a) is performed by providing the step having atapered surface, and wherein said step (c) is performed by disposing theend of the second metallic component in engagement with the taperedsurface.
 12. A method of performing a magnetic pulse welding operationto secure first and second metallic components together comprising thesteps of: (a) providing a first metallic component including a firstportion having a shoulder and a second portion; (b) providing a secondmetallic component having an end; (c) disposing the end of the secondmetallic component in an axially overlapping manner relative to thefirst portion of the first metallic component; (d) providing an inductoraxially overlapping the end of the second metallic component and thefirst portion of the first metallic component; and (e) energizing theinductor to perform a magnetic pulse welding operation to secure the endof the second metallic component to the first portion of the firstmetallic component and to cause the end of the second metallic componentto engage the shoulder to prevent a significant flow of air toward theinductor.
 13. A method of performing a magnetic pulse welding operationto secure first and second metallic components together comprising thesteps of: (a) providing a first metallic component including a firstportion having a shoulder and a second portion; (b) providing a secondmetallic component having an end; (c) disposing the end of the secondmetallic component in an axially overlapping manner relative to thefirst portion of the first metallic component; (d) providing an inductorspaced axially from the end of the second metallic component and thefirst portion of the first metallic component; and (e) energizing theinductor to perform a magnetic pulse welding operation to secure the endof the second metallic component to the first portion of the firstmetallic component and to cause the end of the second metallic componentto engage the shoulder to prevent a significant flow of air toward theinductor.